Process for preparing 1-ethynylcyclohexanol and homologues



PROCESS FGR PREPARING l-ETCYCLO- HEXANOL AND HOMOLOGUES John J. Nedwickand Warren H. Watanabe, Philadelphia, Pa, assignors to Rohm & Haasompany, Philadelphia, Pa, a corporation of Delaware No Drawing. FiledSept. 13, 1957, Ser. No. 683,680

12 Claims. (Cl. 250-531) This invention relates to an improved processfor the production of ethynyl carbinols by a catalytic ethynvlationreaction. More specifically, the invention is concerned with theproduction of ethynylcyclohexanol type compounds from acetylene andcyclohexanone or substituted cyclohexanones employing alkali metalhydroxides as promoters of the reaction. The reaction is carried outentirely in the liquid phase under such high pressures that the reactantacetylene, which is introduced into the reaction zone as a liquidsolution, is maintained in the solvated form throughout the course ofthe reaction.

Processes have been known for the production of acetylenic alcohols. Forexample, U.S. Patent 2,163,720 discloses the reaction of a saturatedketone with an alkali metal hydroxide, followed by treatment of theresulting addition product with acetylene to obtain acetylenic glycolsand alkynyl carbinols. US. Patent 2,302,345 teaches that alcohols andglycols of the acetylene series can be prepared more directly bybringing into contact gaseous acetylene with a mixture of acetone and anaqueous solution having an alkaline reaction. US. Patent 2,712,560describes the ethynylation of formaldehyde using acetylene dissolved ina suitable solvent and a solid heavy metal catalyst. However, thatprocess is not satisfactory for the commercial production of ethynylcarbinols derived from ketones. These and other methods of catalyticethynylation have not been found satisfactory for the preparation ofethynylcyclohexanol type com pounds because, instead of obtainingcommercially practicable yields of the desired carbinol, the productobtained contains an undesirably large amount of glycol and because therate or" conversion to products is undesirably slow.

The present invention is based, in important part, upon the discoverythat if the concentration of acetylene is raised to a high level incomparison with that of the ketone, much higher than it has ever beenemployed in such a reaction before, not only is there obtained a fasterreaction and higher conversion, but there is an entirely differentdistribution of products than is obtained with prior art processes. Inaccordance with the present invention, the glycol, which is one of thetwo normal products of the acetylene plus ketone reaction, is suppressedto a very low level; the carbinol, which is the other normal product, isobtained almost exclusively at production rates averaging over a hundredtimes as much as the best of the prior art processes.

In the prior art Where gaseous acetylene was pressed into the reactionvessel, the concentration of acetylene in the liquid reaction mixture,the actual site of reaction, was limited by the solubility of acetylenein the reaction mixture at the temperature and pressure of reaction.This results in a low ratio of acetylene to ketone, on the order 12,973,390 Patented Feb. 28, 196i ice acetylene per mole of ketone,present in the liquid reaction mixture When it is brought to reactionconditions. The use of such relatively high concentrations of acetylenein the base catalyzed ketone ethynylation reaction permits operation athigher temperatures than have been employed previously and thus a muchhigher rate of reaction is achieved without, at the same time, obtainingexcessive undesirable side reactions such as the base-catalyzed,self-condensation of ketones.

In the prior art methods for producing acetylenic alcohols from ketones,when just the vapor phase system of introducing acetylene was known,there existed only a choice of several evils. The reaction could not becarried out at the high temperatures required to speed the processbecause, aside from the dangers of explosion inherent in heating thegaseous acetylene, it caused excessive side reactions such as thecondensation of ketone mentioned earlier. If the temperature was keptlow, it took very long periods of time to get satisfactory ethynylationresults and, moreover, caused an increase in glycol formation at theexpense of carbinol. In practicing the present invention, use is made ofa condensed phase process which consists in dissolving acetylene in asuitable liquid phase prior to introducing it into a reactor at apressure sufficiently high to maintain the reactants completely in theliquid phase. The condensed phase technique has made it possible toemploy high temperatures without concern over explosions. We have nowfound, moreover, that when the base-catalyzed ethynylation reaction ofacetylene and an appropriate ketone is carried out in the condensed orliquid phase, even though high temperatures are employed there aresubstantially no objectionable side reactions such as were obtained whenthe reaction is performed at equivalent temperatures with the gaseousphase. Not only that, but we have additionally found that with thecondensed phase and the higher temperatures made usable thereby it isnow possible to speed up the reaction considerably, to obtain fargreater yields, and selectively to produce carbinol over glycol in verysatisfactory production quantities. An illustration of the improvedresults which the present invention has made possible over the prior artwill be seen in the following comparison of data from two ethynylationreactions involving cyclohexanone, one by the S; (V)o1ume ketoncconverted to products per hour per volume of reactor ECG- It had beensuggested, prior to our present invention, that the liquid or condensedphase ethynylation process could be carried out by reacting acetylenewith either a ketone or an aldehyde using a solid heavy metal catalystsuch as copper acetylide. Investigation has shown, however, that thisreaction will not work to any significant degree with ketones when suchcatalysts are employed, although it does work quite well with aldehydes.We have now found that this reaction with ketones will only function togive commercially useful yields when 3 the catalyst used is a base suchas potassium or sodium hydroxide.

We have further found that this reaction, even with the base catalyst,will not work with all ketones to an 70% of the total charge, the upperlimit being that at which the catalyst is no longer soluble in thecharge. The alcohol is required to provide catalyst solubility and,together with the. ketone, must provide adequate acetyldroxide. Theketone constitutes approximately 20 to appreciable degree as theequilibrium between carbinol 5 ene solubility. If desired, a thirdliquid component and ketone plus acetylene may be unfavorable and thewhich is primarily a good acetylene solvent (and not base catalyzedcondensation becomes competitive with necessarily a solvent for the basecatalyst too) may be the ethyuylation. The resulting yields, as well asconveradded to improve acetylene solubility. If such a third sions, arelowered. By sharp contrast, we have discomponent is added, however, itmust be one which will covered that one family of ketones, namelycyclohexai0 permit the entire charge to remain homogeneous. The none andsubstituted cyclohexanones, works exceptioncatalyst constitutes 0.5 to'5 wt. percent of the total ally well in this reaction to forml-ethynylcyclohexanol charge. As mentioned earlier, suitable catalystsare and its homologues with percentages of conversion and stronglyalkaline derivatives of the alkali metals, sodium yield which are farhigher than were ever attainable preand potassium, namely potassiumhydroxide and sodium viously, by virtue of which the process has nowbecome hydroxide. A sodium or potassium alkoxide, such as a highlypracticable and productive one, suitable for sodium or potassiummethoxide, ethoxide, butoxide, or commercial operation. An illustrationof the eifectiveethoxyethoxide, is also satisfactory, as are strongorganic ness of the cyclohexanones in comparison with some bases such asbenzyl trimethyl ammonium hydroxide. other ketones in the ethyuylationreaction will be seen As solvents for acetylene there may be employed,for from Table II below: example, dimethyl formal, diethyl formal,dimethyl ace- TABLE 11 Wt. Wt. Aoetylenic Alcohol Percent Percent C2112]Temp., Cont. Ketone Solvent Catalyst Ketone 0. Time Percent PercentMe(OH) (KOH) (m1ns.) Conv. Yield Acetone 1. 1 1. 1 130 9. a 15. 2 33overall 35 1.1 1.4 100 10.0 3. 9 13. as 1.1 1.1 130 10. 0 s. 4 35 1.1 1. 1 130 10.0 no reaction 50 2.0 3.7 140 10.0 no reaction 50 2. 0 a. 1140 10. 0 a. 17. o 27 1.2 1.6 170 4.0 31.2 4&0 27 1. 2 1.8 135 10.0 52.0 70. 0 27 1. 3 2. 0 120 22. 0 40. 0 69. 8 50 2.0 3.0 140 11.0 46.9 85.650 2.0 3.2 140 9.7 30.0 63.0 3,3,5-Trimethylcyclo-hex o 50 2.0 4.0 14010.6 8.0 64.0 4-tert-Octylcyclohexanone 50 2. 0 4. 7 140 10. 0 35. 7 54.0

Set forth below are a number of examples which fully tal, diethylacetal, dioxane, dioxolane, Z-methyl dioxodescribe the method of thepresent invention and give lane, the monomethyl, dimethyl, monoethyl,diethyl, the details of the experiments by which the data in Tablemonopropyl, dipropyl, and butyl ethers of ethylene II was obtained.However, some general comments on glycol, the dimethyl ethers ofdiethylene glycol, triethylthe method beforehand will be in order toassist all ene glycol, or tetraethyleue glycol, tetrahydrofuran, ethylthose interested in practicing this invention. ether, isopropyl ether,N-methyl pyrrolidone-Z, dimethyl In the first place, acetylene gas is:not handled at formamide, and dimethyl sulfoxide. Mixtures of twoelevated temperatures, nor need it be diluted. It is disor more of suchsolvents may be used. The amount of solved in the cold reaction mixtureunder superatmossolvent may vary from zero up to or more of the phericpressures, preferably from 100 to 500 p.s.i.g. with 50 reaction mixture.Of course, the best eiiiciency is had the exercise of the usualprecautions except that dilution when the amount of solvent is kept to aminimum for with gas or vapor is unnecessary at the absorbingtemabsorbing the required amount of acetylene and for mainperature used,usually between -20 and 30 C. Even taining the mixture fluid at lowesttemperature of abhigher pressures may be used, but normally they are notsorption. needed to get the required amount of acetylene into Themixture charged with acetylene is passed in liquid solution. Lowertemperatures may be employed to in-' phase through a heating zone, wherethe reaction mixcrease the solubility of the acetylene short of thefreezing ture is heated to a reacting temperature from about point, butgenerally it is not economical to go below to 170 C., preferably to C.under pressure the indicated preferred limits. Higher temperatures aresuflicient to maintain the liquid phase. This requires usable also, butagain are not desirable because of the 60 pressures from about 1000 to5000 p.s.i.g. Residence dangers involved in the lowering of theacetylene solutime in the heating zone is from about one to ten minutes.bility and the fact that the ethyuylation reaction may Longer times canbe used, but usually without advanbe started before all the acetylene isdissolved. Enough tage. Generally, with a residence time of two to fiveacetylene is dissolved in the reaction mixture to provide minutes, themajor portion of the ketone will have re at least one mole per mole ofketone present. Higher 65 acted cleanly. The balance may take up toeight minutes concentrations will give improved yields and conversionsbut ten minutes allows a reasonable factor of safety of ketone tocarbinol. The excess acetylene can be reto assure that the process iscomplete. covered and recycled. A concentration of from 1.1 to In aconvenient form of apparatus the reaction mix- 3 moles of acetylene permole of ketone is preferred. ture is passed continuously through aheated tubular re- The reaction mixture is a homogeneous, one-phase 7oactor. Reaction takes place with evolution of heat which liquidconsisting of ketone, an auxiliary solvent such as is dissipated and thetemperature controlled within the methyl alcohol, ethyl alcohol,isopropyl alcohol, or some desired limits. In this manner of operation,it is possible other lower alkanol which helps to solubilize the catatoobserve, with the aid of thermocouples, that reaction lyst and is also agood solvent for acetylene, and a disis very rapid and becomesessentially complete within the solved strongly basic catalyst such aspotassium hy- 76 ten minute residence-or contact time mentioned above.

The reaction mixture now is worked up by any suitable conventionalmethod to give the ethynylcyclohexanol type product. Pressure isreleased. If desired, the mixture may be degassed. The volatile portionsare distilled off and the product is purified.

The solvent used can be recycled. Unreacted ketone and the residuecontaining catalyst can be recycled with the addition of catalyst asneeded, although from time to time at least portions of the residue mustbe withdrawn and replaced with fresh catalyst.

In the following examples, which are presented for purposes ofillustration and not by way of limitation, additional details ofprocedure are presented. Parts are by weight unless otherwisedesignated. The examples, it will be noted, are summaries of theexperiments which were performed to obtain the data set forth in Table Habove.

Example 1 To a flask equipped with a stirrer there was charged 117 partsof methyl alcohol and 5.3 parts of potassium hydroxide. When all of theKOH had dissolved, there was added 294 parts of cyclohexanone. Thissolution was now charged to a suitable vessel and acetylene passed inuntil 143 parts had been absorbed. The pressure was 300 p.s.i.g. and thetemperature 7 ,C.

This mixture was now passed through a tubular reactor maintained at 135C., and a pressure (1500 p.s.i.g.) sufficient to prevent the desorptionof acetylene. The contact time was 10.0 minutes.

The reactor effluent was collected continuously during the course of thereaction. When the reaction was completed, the entire reaction mixturewas degassed and then vacuum flash-distilled at a pressure of 0.3 mm.and pot temperature to 100 C. The flash-distillate was fractionatedthrough an appropriate column to recover methyl alcohol, l-ethynylcyclohexanol, cyclohexanone, and 1- 2-bis(cyclohexanol-1)-ethyne. Theproduct (l-ethynyl cyclohexanol) came over at 6870 C./ mm., n 1.4802.Conversion was 52% and the yield 70%. The acetylenic glycol wasrecovered from the distillation bottoms by recrystallization from carbontetrachloride. Conversion to the glycol (M.P. 107 C.) was 7.5% and theyield 10.3%. Overall yield of products, based on cyclohexanone, was80.3%.

Example 2 The procedure was exactly the same as in Example 1 except thatan equivalent amount of potassium methoxide was used in place of thepotassium hydroxide, and an equivalent result was obtained.

Example 3 Procedure was the same as in Example 1 except that thetemperature was 170 C. and the holding time 4.0 minutes. Conversion tol-ethynyl-cyclohexanol was 31.2% and the yield 46%.

Example 4 The procedure was exactly the same as in Example 3 except thatan equivalent amount of sodium methoxide was used in place of thepotassium hydroxide, and an equivalent result was obtained.

Example 5 Procedure was the same as in Example 1 except that thetemperature was 120 C. and the contact time 22.0 minutes. The conversionto l-ethynyl-cyclohexanol was 40% and the yield 69.8%.

Example 6 To 200 parts of methyl alcohol there was added 8.2 parts ofKOH. When all of the KOH had dissolved there was added 199 parts of3-methy1 cyclohexanone. This solution was now charged to an appropriatevessel and acetylene passed in until 130 parts were absorbed. Thepressure was 250 p.s.i.g. and the temperature 12' C.

Procedure was identical with Example 6 except for the starting materialwhich in this instance was 2-methylcyclohexanone. Conversion tol-ethynyl-Z-methyl cyclohexanol was and the yield 63%. The boiling pointwas 7l-72 C./ 10 mm. Analysis for acetylenic hydrogen indicated materialwas 94% pure.

Example 8 Procedure was identical with Example 6 except for the startingmaterial which in this instance was 4-t-octylcyclohexanone. Conversionto 1-ethynyl-4-tert octyl cyclohexanol was 35.7% and the yield 54%. Theboiling point was 97 C./ 0.45 mm. Analysis indicates material was 80%pure.

Example 9 Procedure was identical with Example 6 except that3,3,5-trimethyl-cyclohexanone was used as the starting material.Conversion to 1-ethynyl-3,3,5-trimethyl cyclohexanol was 8.0% and theyield 64%.

A variety of other ketones, aliphatic, cycloaliphatic and aromatic, weretried in similar fashion. As shown in Table II, the conversions andyields of product were much lower than in the case of cyclohexanone.

We claim:

1. A process for the production of l-ethynyl-cyclohexanol and homologuesthereof which comprises dissolving acetylene under a pressure of atleast about pounds per square inch and at a temperature up to about 30C. in a liquid phase com-prised of a mixture of (1) a ketone from theclass consisting of cyclohexanone and alkyl-substituted cyclohexanonesin which the alkyl group is in the range of C to about C (2) an alcoholfrom the group consisting of methanol, ethanol, and isopropanel, and (3)an ethynylation catalyst from the group consisting of sodium andpotassium alkoxides in an amount which constitutes from about 0.5 toabout 5.0 weight percent of the total charge, the amount of acetylenepresent being in the ratio of at least one mole per mole of the ketone,passing this reaction mixture through a reaction zone where the mixtureis heated to at least about 100 C. under a pressure of at least 1,000p.s.i.g. so as to prevent the formation of a vapor phase, and

thereafter separating the ethynyl carbinol formed thereby from theeffiuent from the reaction zone.

2. The process of claim 1 in which the alcohol constitutes from about 10to about 50% of the reaction mixture.-

3. The process of claim 1 in which the ketone con- 5. A process for theproduction of ethynyl carbinols by the catalytic ethynylation of aketone in which there is formed a major amount of the carbinol and onlya minor amount of the corresponding acetylenic glycol, said processcomprising dissolving from 1 to 3 moles of acetylene per mole of ketonein a liquid mixture of a ketone from the class consisting ofcyclohexanone and 'alkyl-substituted cyclohexanones in which the alkylgroup is in therange of C to about C an alcohol from the groupconsisting of methanol, ethanol and isopropanol, and an ethynylationcatalyst from the group consisting of sodium and potassium alkoxides inan amount which constitutes from about 0.5 to about 5.0 weight percentof the total charge, the solution of acetylene being carried out at apressure of from 100 to 500 lbs/in. and a temperature up to about 30 C.,reacting the acetylenerich reaction mixture at a temperature of between100 and 170 C. and a pressure between 1,000 and 5,000 lbs./in. andthereafter recovering the ethynyl carbinol by separating it from theeffluent of the reacted mixture.

6. The process of claim 5 additionally including in the reaction mixturean inert solvent for acetylene, the amount of which may be as much as50% of the reaction mixture.

7. The process of claim 5 in which the residence time during which thereaction mixture is maintained at the elevated temperature is from about2 to about minutes.

8. The process of claim 5 in which the ketone used is cyclohexanone.

9. The process of claim 5 in which the ketone used is 2-methylcyclohexanone.

10. The process of claim 5 in which the ketone used is Zfimethylcyclohexanone.

11. The process of claim 5 in which'the ketone used is 3,3,5-trimethylcyclohexanone.

12. The process of claim 5 in which the ketone used is 4-tert-octylcyclohexanone.

References Cited in the file of this patent UNITED STATES PATENTS2,302,345 Pesta Nov. 17, 1942 2,385,548 Smith Sept. 25, 1945 2,455,058Herman Nov. 30, 1948 2,712,560 McKinley et a1. July 5, 1955 2,858,344Kleinschmidt et a1. Oct. 28, 1958 FOREIGN PATENTS 589,350 Great BritainJune 18, 1947 1,091,401 France Oct. 27, 1954 OTHER REFERENCES Reppe:Acetylene Chemistry" (P.B. Report 18852-8), Charles A. Meyer and Co.Inc. (translation), 1949, N.Y., pages 82 and 83.

1. A PROCESS FOR THE PRODUCTION OF 1-ETHYNYL-CYCLOHEXANOL AND HOMOLOGUESTHEREOF WHICH COMPRISES DISSOLVING ACETYLENE UNDER A PRESSURE OF ATLEAST ABOUT 100 POUNDS PER SQUARE INCH AND AT A TEMPERATURE UP TO ABOUT30*C. IN A LIQUID PHASE COMPRISED OF A MIXTURE OF (1) A KETONE FROM THECLASS CONSISTING OF CYCLOHEXANONE AND ALKYL-SUBSTITUTED CYCLOHEXANONESIN WHICH THE ALKYL GROUP IS IN THE RANGE OF C1 TO ABOUT C8, (2) ANALCOHOL FROM THE GROUP CONSISTING OF METHANOL, ETHANOL, AND ISOPROPANOL,AND (3) AN ETHYNYLATION CATALYST FROM THE GROUP CONSISTING OF SODIUM ANDPOTASSIUM ALKOXIDES IN AN AMOUNT WHICH CONSTITUTES FROM ABOUT 0.5 TOABOUT 5.0 WEIGHT PERCENT OF THE TOTAL CHARGE, THE AMOUNT OF ACETYLENEPRESENT BEING IN THE RATIO OF AT LEAST ONE MOLE PER MOLE OF THE KETONE,PASSING THIS REACTION MIXTURE THROUGH A REACTION ZONE WHERE THE MIXTUREIS HEATED TO AT LEAST ABOUT 100*C. UNDER A PRESSURE OF AT LEAST 1,000P.S.I.G. SO AS TO PREVENT THE FORMATION OF A VAPOR PHASE, AND THEREAFTERSEPARATING THE ETHYNYL CARBINOL FORMED THEREBY FROM THE EFFLUENT FROMTHE REACTION ZONE.